I successfully installed 2 CAS servers and was moving on to the Hub Transport servers, but during the install (at the end) setup threw an error... The setup log information did not provide very good troubleshooting information nor did the event id lookup. I am positive our domain controllers are functioning as they should as i had to make some recommended changes (based on EBPA) and watch them replicate. I am at a loss, has anyone seen this error? Also, this is a coexistance with exchange 2003 if that lends any info... Event Type:ErrorEvent Source:MSExchangeSetupEvent Category:Microsoft Exchange Setup Event ID:1002Date:5/17/2007Time:1:10:10 PMUser:N/AComputer:MUXCHUB02Description:Exchange Server component Hub Transport Role failed. Error: Error:Active Directory operation failed on my domain controller (actual name taken out for security reasons). This error is not retriable. Additional information: The name reference is invalid.This may be caused by replication latency between Active Directory domain controllers.Active directory response: 000020B5: AtrErr: DSID-03152392, #1:0: 000020B5: DSID-03152392, problem 1005 (CONSTRAINT_ATT_TYPE), data 0, Att 7fac30e2 (msExchTargetBridgeheadServersDN) A value in the request is invalid. Error:Active Directory operation failed on my domain controller (actual name taken out for security reasons). This error is not retriable. Additional information: The name reference is invalid.This may be caused by replication latency between Active Directory domain controllers.Active directory response: 000020B5: AtrErr: DSID-03152392, #1:0: 000020B5: DSID-03152392, problem 1005 (CONSTRAINT_ATT_TYPE), data 0, Att 7fac30df (msExchSourceBridgeheadServersDN) A value in the request is invalid. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

You could try adding the /dc:anotherdcname to the end of the setup command line to force it to look at another DC during setup. I think this could be related to DC's which have previously been removed from your AD Domain without properly being demoted, orphaned/latent objects that still exist but not visible. You should run DCDiag /e /c /v /f:x:\logfile on one of your DC's to check the health of DC's in your domain. In co-existance it is recommended to suppress linkstate propegation on all existing Exchange 2003 Servers in your domain before installing Exchange 2007 Servers to your organization. http://technet.microsoft.com/en-us/library/aa998953.aspx